THE LONGEVITY OF TREES. 321 



every case of automatic Mental activity ? whether this be left alto- 

 gether uncontrolled, or be in subjection to the will. 



9. "When a series of Physical sequences comes to be established by 

 the Habitual action of the Cerebrum in particular modes directed or 

 permitted by the Will, is it not consonant to all Physiological proba- 

 bility that the tendency to similar sequences should be hereditarily 

 transmitted, like the tendency to bodily habits ? Contemporary Re- 

 view. 



-- 



THE LONGEVITY OF TKEES. 



By ELIAS LEWIS. 



IN the vegetable world, limits of growth and life are strangely 

 diversified. Multitudes of forms mature and perish in a few days 

 or hours ; while others, whose beginning was in a remote antiquity, 

 have survived the habitual period of their kind, and still enjoy the 

 luxuriance of their prime. Some species of unicellular plants are so 

 minute that millions occur in the bulk of a cubic inch, and a flowering 

 plant is described by Humboldt, which, when fully developed, is not 

 more than three-tenths of an inch in height. On the other hand, we 

 have the great Sequoia, whose mass is expressed by hundreds of tons, 

 and specimens of the Eucalyptus, growing in the gulches of Australia, 

 surpass in height the dome of St. Peter's. 



Some of the Fungi mature between the setting and rising of the 

 sun, while the oak at our door, which awakens the memories of our 

 childhood, has not perceptibly changed in bulk in half a century. 

 Trees grow more slowly as they increase in age. Nevertheless, it is 

 certain that growth continues while they continue to live. The devel- 

 opment of foliage implies interstitial activity and organization of new 

 material. In its vital processes there is little expenditure of force or 

 waste of substance. Its functions are essentially constructive, and its 

 growth and age are apparently without limits, excepting such as arise 

 from surrounding conditions. Thus many trees represent centuries, 

 and have a permanence that is astonishing and sublime. Travellers 

 stand awe-struck before the monuments which for forty centuries have 

 kept watch by the Nile, but the oldest of these may not antedate the 

 famous dragon-tree of Teneriffe. It is not surprising that the ancients 

 considered trees " immortal," or, as " old as Time." 



But, if the life of the tree is continuous, its leaves the organs of 

 its growth have their periods of decay, and are types of mortality. 

 The life of man is likened to the " leaf that perishes." In an animal, 

 the vital processes are carried on by a single set of organs, the im- 

 pairment of which limits the period of its life. With the tree, decay 



VOL. III. 21 



